Engine piston



R. N. STEELE Nbv. 15, 1932.

ENGINE PISTON Filed Jan. 17. 1930 Patented Nov. 15, 1932 UNITED STATES RAY N. STEELE, OF CEDAR'RAP-IDS, IOWA ENGINE sist r Application filed January 17, 1930 Serial No. 421,426. i

This invention relates to the pistons of internal combustion engines, more particularly those applied to automobiles and other motor vehicles. Specifically it relates to a type of piston described in a former application for patent by this inventor, which was filed July 12, 1928, numbered 292,196, and

is a continuation in part thereof. 1

One of the main objects of the invention is to reduce the weight of the piston to a minimum by the use of light material, such as an aluminum alloy, for the principal structure, but impart to it durability and satisfactory wearing qualities by partially sheathing the body with a reinforcing ring or slhell of wear-resisting material, such as stee A further object is to provide for'the initial close fitting of the piston to the cylinder by the use of a steel having a very low coefiicient of expansion, as a reinforcing element.

A further object is to provide for the free radiation of heat from the head of the piston, and diffusion thereof through the piston skirt.

A still further obj ect is to provide for such a construction of the piston internally that the piston may be finished on a lathe, and

0 with a minimum of chucking operations.

In the accompanying drawing, forming a part of this specification, Fig. 1 is a plan view of a piston embodying the inventio as seen from the open end. Fig. 2 is a section of the same, on the line 2 2 of Fig. 1. Fig. 3 is a section on the line 33 of Fig. 1, and shows also a means of swaging the body of the piston into firm and close contact with the external ring.

The main body of the piston, hereafter des with the posts is by threadedsleeves 9 set rigidly in the posts, as by'casting therein. To prevent any possible stripping of the sleeves from the posts the sleeves should be externally ribbed or corrugated. The studs are screwed tightly into the sleeves or sockets after the ends of the posts havebeen faced to receive the wrist-pins, which work may be done by"thellathe while the piston 'is chucked forother operations.

From the piston-head extends bular'skirt 6 formed as a part-:of-the same casting of aluminum, or the like light material. "The poor wearing qualities of such metal is offset by'its high conductivity of heat, and the skirt is-accordingly best made of full length, with a terminal zone 60, to make contact with the cylinder-walls, since it is of prime importance that the high heat a thin I of the head, incident to explosion, be radiatedaway therefrom as rapidly and com pletely as possible. This is effected by-the continuous, thin skirt, and its contact with the cylinder. 1 8

Adequate wear and anice and practically unvarying fit of thepiston in the cylinder is supplied by'an external band 7 of steel fit. ting in agroove of the skirt. In practice the preferred metal for this purposeis what is 7 known as .invar? steel, which has such a low coefficient of expansion that the variation between normal and high heat is negligible. It may therefore be fitted initially to the'bore of the, cylinder, with little danger of jam ming when the piston becomeshot. p A simple manner of attaching the band to the skirt is to cast the skirt inside the band. As the'casting cools the higher expansibility of the casting naturally tends to loosen it from the inside of theband by shrinkage, though the contact may still be tight at the edges. It is desirable, however, that a portion of theinside of the band, at least, fit snugly on the skirt. This may be effected by expanding the skirt, or a zone of the same near the lower end, until such a close fit in the band is secured. This may be done, by the use of compression; rollers 11, as shown in Fig. 3. When so expanded theskirt will oficourse-tend toexpand still more .bythe heat of combustion, andto counteract this the skirt is slotted at 12, so that under changes of temperature the skirt may come and go, to the necessary limited extent.

The relative width of the steel band and the terminal zone of the skirt are herein indicated only approximately, the exact relative width for all conditions being a matter to be determined experimentally.

Having thus described my invention, I claim:

1. An engine piston having a head and a tubular lower extension forming a skirt, the same being-laterally imperforate, a pair of internal posts detached from the side walls and extending from the closed end,sleeves within said posts and rigidly united therewith, said sleeve-extending at least to the free ends of the posts, .a wrist-pin flattened upon one side of each end, to rest on the ends of the sleeves, fastening bolts connected with the sleeves and passing through the pin, and means on said bolts engaging said pin and holding same against said sleeve. I

2. An engine piston having a head and a tubular skirt extending therefrom, a pair of internal soft metal posts detached from the side walls and extending from the closed head, internally screw-threaded sleeves set tightly in said posts and having their exposed ends flush with the free ends of the posts, pin-fastening bolts engaging said sleeves, and a wrist-pin mounted on said bolts and held against the exposed ends of the sleeves.

3.. An engine piston having a head and a tubular extension forming a skirt, the same being laterally imperforate, a pair of internal posts depending from the inner face of the head, sleeves within said posts and immovably connected therewith, a wrist-pin flattened at its ends, on one side, to rest against the ends of the sleeves, fastening bolts threaded into said sleeves and passing through the pin, and means on said bolts engaging said pin and holding same tightly against the ends of said sleeves.

4. An engine piston having a head and a tubular skirt extending therefrom, a pair of internal, light, metal posts depending from the inner face of said head, internally screwthreaded sleeves within said posts and rigidly united'thereto,'said sleeves having their exposed ends substantially fiush with the free ends of the posts, pin-fastening bolts engaging said sleeves, and a wrist-pin perforated adjacent its ends mounted on said bolts and held against the exposed ends of the sleeves.

5. An engine piston having an expansible skirt of light material, as aluminum, and a non-expansible metal band within which the skirt is cast, a portion of the skirt within the band being expanded after shrinkage to fit tightly within the band. 6. An engine piston having an external skirt-band of steel, and an aluminum body with a skirt disposed within the skirt-band compensate for its excess of expansion and contraction.

In testimony whereof I afiix mysignature.

RAY N. STEELE. 

